1. Field of the Invention
The present invention relates to the synthetic amorphous precipitated alumino silicates and more particularly to the production of amorphous sodium alumino silicates having increased ion or base exchange properties.
2. The Prior Art
Cation exchangeable materials and their use, for example, in water softenings, are well known in the art. While many products are known to posses such properties, in general, a particularly suitable class of ion exchangers are the so-called zeolites, which occur naturally in nature or may be produced synthetically. Crystalline alumino silicate zeolites structurally consist basically of an open three-dimensional framework of SiO.sub.4 and AlO.sub.4 hedrahidra. Specific examples of synthetic zeolites, methods for their production as well as their use as ion exchangers, adsorbents and the like are disclosed in U.S. Pat. Nos. 2,882,243; 3,008,803; 2,962,355; 2,996,358; 3,010,789; 3,012,853; and 3,130,007. Other known base exchange materials are base exchange gels which are granular products made by the reaction of sodium silicate and aluminum compounds. These products have to some extent been used for large-scale water softening and remove calcium and magnesium from water and may be regenerated by passing a solution of NaCl through a filter bed of the hard granules. In this regard see U.S. Pat. Nos. 1,586,764; 1,717,777; 1,848,127; and British Pat. No. 177,746.
In recent years a number of synthetic amorphous, precipitated sodium alumino-silicate pigments, manufactured and sold under the trademark "Zeolex", have been prepared. Examples of these products, and methods for their preparation, are disclosed in U.S. Pat. Nos. 2,739,073 and 2,848,346. Such pigments have been found to be useful in a wide range of applications such as fillers and reinforcing pigments for rubber compounds, plastics, paper and paper coating compositions, paints, adhesives, etc. While such amorphous sodium alumino-silicate pigments have been found to be useful in such applications, their use as a base or ion exchange product has heretofore been considered impractical because of their low exchange capabilities.